7 


Hawaii  Agricultural  Experiment  Station, 


HONOLULU 


J.  G.  SMITH,  Special  Agent  in 


PRESS  BULLETIN  No.§£? 


THE  COMMON  LIVER  FLUKE  /J&A>IVAZ/.         V&V* 

X*^ &&/ 

(Distoma  hepaticum )  ^rVfffflfHlft '^ 

The  fact  that  990  cattle  out  of  3,376  slaughtered  for  the  Hono- 
lulu market  during-  a  period  of  six  months  in  1902  showed  an 
infection  of  the  liver-fluke  and  that  in  certain  districts  this  para- 
site has  become  epizootic  among  cattle,  calls  for  a  brief  compila- 
tion concerning  the  disease,  its  cause,  transmission  and  remedies. 
An  earlier  record  places  the  number  of  fluky  cattle  killed  for  mar- 
ket still  higher.  "In  some  parts  of  Oahu  nearly  all  the  cattle 
have  been  destroyed  by  the  disease ;  the  sheep  from  dry  districts, 
however,  are  not  affected.  Of  602  calves  examined  at  Honolulu, 
298  were  found  infested;  of  2,186  cattle,  1,313  were  infested,  so 
that  about  four-sevenths  of  the  animals  were  diseased.""' 

The  disease  is  not  confined  to  cattle,  and  because  of  its  varying 
symptoms,  duration  and  variety  of  hosts  has  received  numerous 
common  names,  the  most  familiar  of  which  are,  perhaps,  the 
"sheep-rot"  and  "liver-rot."  The  hosts  of  the  adult  of  this  species 
are  man,  cattle,  sheep,  swine,  cats,  rabbits,  horses,  goats,  deer, 
and  other  vertebrates,  and  during  one  phase  of  its  intermediate 
development,  certain  fresh-water  snails  (Mollusca).  The  disease 
caused  by  this  parasite  has  been  especially  destructive  to  sheep 
with  the  injury  to  cattle  and  swine  next  in  importance.  From 
reports  it  would  seem  that  in  no  other  portion  of  the  United 
States  has  its  attack  on  cattle  been  as  serious  as  in  Hawaii. 

What  the  common  liver-fluke  is: — The  parasite  is  one  of  the 
flat-worms  (Trematoda)  known  to  science  as  Distoma  hepaticum. 
In    appearance    it    is    perfectly    flat,    unsegmented    and    leaf-like 


*  Bulletin  19.    BureaufDf  Animal,  lad  uqti'y,  US    nppnrtrpent  of  Agri- 


r^wmm, 


culture.     189S,  p.  42.       /  DQgUMgNTfi  f)ftt>T 


U.S.  DEPOSITORY 


and  the  specimens  taken  from  infected  cattle  varied  from  J  inch 
to  I  inch  in  length.  (See  Plate  I.  G  and  H.)  It  infests  in  cattle 
the  liver,  gall-bladder,  bile-ducts,  and  has  been  found  in  the  lungs. 

Tlie  life  history  of  the  common  liver-fluke: — (See  Plate  I.) 
The'  life-history  of  the  fluke  is  a  very  complicated  affair,  occupy- 
ing from  10  to  12  weeks.  A  brief  statement  of  the  important 
phases  is  sufficient  for  the  purposes  of  this  paper.  The  eggs  (see 
Plate  I.  A  and  B)  of  an  adult  fluke,  numbering  from  37,000  to 
45,000,  pass  from  the  liver  of  the  infested  stock,  through  the  bile- 
ducts  to  the  stomach  and  then  to  the  intestine,  from  which  they 
are  expelled  with  the  faecal  matter  and,  to  further  develop,  must 
fall  or  be  washed  into  water.  In  water,  and  water  only,  there 
develops  within  the  Qgg  a  ciliated  embryo  which  finally  bursts 
through  the  eggshell  and  swims  actively  about.  To  further  de- 
velop this  organism  must  find  or  come  in  contact  with  certain 
fresh-water  snails.  Two  species  of  these  intermediate  hosts  are 
recorded  from  these  Islands,  Limnaea  oahuensis  (see  Plate  I. 
I  and  J)  and  Limnaea  rubella.  The  former  species  occurring  on 
Oahu  and  Maui  and  the  latter  on  Oahu  and  Kauai.* 

It  is  probable  that  one  or  both  species  are  generally  distributed 
over  the  Islands,  but  if  certain  districts  are  free  from  these  species 
the  stockmen  of  those  districts  have  certainly  reason  for  self-con- 
gratulation, since  because  of  their  part  in  the  transmission  of  the 
liver-fluke  disease,  their  presence  is  equally  as  dangerous  to  the 
interests  of  the  ranchers  as  the  presence  of  the  fluke  itself.  To 
continue  with  the  life-history, — these  swimming  ciliated  embryos 
(miracidiitm),  (see  Plate  I,  C, )  minute  in  size,  bore  their  way 
into  the  body  of  the  snail,  if  fortunate  enough  to  find  a  host,  and 
seek  lodgment  in  the  liver  or  other  parts  of  the  body.  Here 
another  change  in  the  life-cycle  occurs.  The  organism  becomes 
quiet  and  forms  what  is  known  as  a  sporocyst.  (See  Plate  I,  D.)  In 
this  inactive  state  each  sporocyst  gives  rise  to  from  5  to  8  organisms 
within  itself  called  rcdiac.  These  rediae  may  be  considered  a  sec- 
ond generation  of  the  immature  liver-fluke  which  leave  the  spor- 
ocyst when  fully  developed  and  seek  the  liver  of  the  snail,  if  not 
already  lodged  there.  Within  the  liver  of  the  snail  there  is  still 
another  multiplication  of  individuals,  that  is,  each  redia  (see 
Plate  I.  E.)  gives  rise  to  from  12  to  20  further  organisms  known 


*  Fauna  Hawaiiensis.     Vol.  II.     Part  IV,  pp.  392,  393. 


as  cercariae.  This  further  development  makes  still  a  third  gen- 
eration. The  cercariae  pass  from  the  body  of  the  snail  into  the 
water  and  attach  themselves  to  blades  of  grass  (see  Plate  I.  F.) 
or  such  plants  as  may  occur  in  or  about  any  standing  water;  or, 
during  a  time  of  high  water,  they  may  be  carried  out  on  the 
range  and.  when  the  water  recedes,  left  on  the  grass  some  dis- 
tance away  ;  or,  again,  they  may  be  washed  from  the  higher  levels 
to  fields  below.  On  becoming  attached  to  the  blades  of  grass  or 
the  stems  of  other  plants,  the  cercariae  become  encysted,  or  dor- 
mant again,  and  so  remain  for  an  indefinite  period,  until  swal- 
lowed with  the  grass  or  other  forage  plant  eaten  by  the  stock. 
Local  infection  has  been  traced  to  the  feeding  to  cattle  of  a  much- 
prized  forage  plant  known  as  hono-hono  (Commelina  nudiflora), 
which  grows  abundantly  about  water-courses  throughout  the 
Islands.  In  the  stomach  of  cattle  or  other  animals  eating  plants 
thus  infested  with  the  encysted  cercariae,  the  cyst  or  covering  is 
destroyed  and  the  undeveloped  liver-fluke,  becoming  active  again. 
seeks  the  liver  of  the  host  through  either  the  gall-ducts  or  portal 
veins,  and  develops  into  the  adult  fluke,  already  mentioned,  thus 
completing  the  life-cycle. 

1  he  immense  number  of  eggs  and  the  large  increase  of  each 
intermediate  generation  would  mean  an  increase  of  the  adult 
fluke  almost  beyond  numbers,  were  it  not  for  the  small  chance 
any  one  individual  has  of  reaching  maturity.  In  the  first  place, 
few  indeed  of  the  eggs  in  the  faecal  matter  find  their  way  to 
water  in  which  they  may  hatch  into  the  second  stage.  Again, 
not  all  of  the  resulting  ciliated  embryos  in  the  water  succeed  in 
finding  the  particular  fresh-water  snails  which  are  their  special 
hosts.  Failure  to  find  the  proper  snail  results  in  extermination. 
Finally,  not  all  of  the  encysted  undeveloped  flukes  on  the  blades 
of  grass  are  eaten  by  stock.  However,  it  can  be  plainly  seen  that 
where  conditions  are  favorable,  that  is,  where  standing  water 
abounds  where  the  snails  are  present  and  about  which  fluke- 
infested  stock  are  feeding,  the  liver-fluke  disease  can  readily 
become  epizootic. 

Symptoms  of  the  disease  in  cattle: — "The  first  symptoms  are 
generally  overlooked,  the  disease  not  attracting  attention  until 
the  appetite  is  diminished,  rumination  (chewing  the  cud)  be- 
comes irregular,  the  animals  become  hidebound,  and  the  coat  dull 
and  staring.  The  staring  coat  is  due  to  the  contraction  of  the 
muscles  of  the  hair  follicles.     The  visible  mucous  membranes  be- 


come  pale,  eyes  become  dull,  there  is  running  at  the  eyes,  and  the 
animal  gradually  becomes  emaciated.  As  the  disease  advances 
the  milk  supply  is  lessened,  fever  appears,  there  is  generally  great 
thirst,  but  the  appetite  almost  ceases ;  oedematous  ( dropsical ) 
swellings  appear  on  the  belly,  breast,  etc. ;  diarrhoea  at  first  alter- 
nates with  constipation,  but  finally  becomes  continuous.  The  dis- 
ease lasts  from  2  to  5  months,  when  the  most  extreme  cases  suc- 
cumb."* Animals  observed  in  the  last  stages  of  the  disease,  on 
the  windward  side  of  Oahu,  could  be  distinguished  from  the  rest 
of  the  herd  because  of  their  standing  alone,  with  head  up  and 
apparently  without  inclination  to  eat  or  move.  Several  post- 
mortems were  made  and  notes  taken  in  regard  to  the  symptoms. 
The  blood  had  become  almost  free  from  red  corpuscles.  Effusion 
of  the  blood  serum  had  occurred  into  the  abdominal  and  lung  cav- 
ities. In  every  case  enormous  numbers  of  flukes  were  found  in 
the  liver,  gall-bladder  and  bile-ducts.  In  the  final  stages  the  res- 
piration becomes  rapid  and  towards  the  last  breathing  becomes 
very  difficult,  due  to  the  extension  of  the  dropsical  swellings, 
occurring  along  the  under  side  of  the  body  to  the  neck  and  throat 
so  that  the  animal  apparently  dies  from  suffocation  and  starva- 
tion. 

Determination  of  the  presence  of  flukes: — The  eggs  may  be 
discovered,  if  present,  by  a  microscopical  examination  of  the 
faecal  matter,  or  a  suspected  animal  slaughtered  and  its  liver  and 
bile-ducts  examined  for  the  flukes  themselves.  If  the  cattle  are 
found  to  be  fluky  it  would  be  better  to  slaughter  them  for  the 
market  at  once  since  in  the  early  stages  of  the  disease  they  have 
a  tendency  to.  fatten,  owing  to  the  excessive  secretion  of  the  diges- 
tive ferments,  and  not  only  would  there  be  a  better  return  for  the 
stock  but  also  by  destroying  the  infected  organs  and  contents  of 
the  intestines,  the  spread  of  the  disease  would  be  checked. 

Where  flukes  may  be  expected  to  be  found: — In  general  the 
statement  is  correct  that  flukes  may  abound  wherever  the  condi- 
tions are  suitable  for  the  life  of  its  intermediate  host,  the  fresh- 
water snail.  This  would  mean  any  range  or  pasture  containing 
a  body  of  water  or  marshy  place  harboring  this  snail :  and,  the 
previous  introduction  of  the  fluke.  Stockmen  should  be  careful 
not  to  take   fluky  cattle   from   place   to  place  and  by   no  means 


*  Bulletin  19,  Bureau  of  Animal  Industry,  U.  S.  Department  of  Agri- 
culture. 


purchase  stock  from  a  fluke-infested  district.  A  law  forbidding 
the  sale  of  infested  stock  except  for  the  market  and  providing 
for  the  inspection  of  ranges  with  the  power  of  enforcing  the  dis- 
use of  areas  and  localities  found  to  be  fluke-infested  until  proper 
precautions  were  taken  would  do  much  towards  lessening  the 
spread  of  the  disease  and  checking  its  serious  inroads  into  the 
herds  of  these  Islands. 

Remedies: — Slaughtering  and  marketing  fluky  cattle  before  the 
last  stages  of  the  disease  is  undoubtedly  the  most  practical  method 
of  stamping  out  infection.  The  liver  is  the  only  part  of  the  car- 
cass rendered  unfit  for  food  and  great  care  should  be  taken  to 
destroy  this  organ,  the  gall-bladder,  bile-ducts  and  contents  of 
the  intestines.  Xo  drugs  or  mixtures  have  been  found  by  which 
the  disease  can  be  successfully  treated.  However,  in  case  a  val- 
uable animal  is  seriously  affected  an  improved  diet  together  with 
liberal  use  of  stimulants  and  tonics  will  in  many  cases  build  up 
the  system  and  general  vitality  so  that  the  animal  may  live 
through  the  fourth  stage  of  the  disease,  when  the  flukes  will  die 
or  wander  out  from  the  infested  organs  spontaneously.  This 
treatment  would  include  the  use  of  cocoanut  meal,  bran  and  mill 
feeds,  with  daily  doses  of  the  various  iron  salts,  walnut  leaves, 
calamus  and  gentian.  These  remedies  would  only  be  applicable 
to  the  treatment  of  milch  cows  and  fine  breeding  stock. 

Precautionary  measures: — The  following  preventive  measures 
for  controling  the  liver-fluke  disease  are  taken  from  Bulletin 
Xo.  19  of  the  Bureau  of  Animal  Industry,  United  States  Depart- 
ment of  Agriculture : 

To   prevent  the  scattering   of  eggs  in  the  fields: 

In  buying  cattle  or  sheep,  do  not  purchase  any  from  a  fluky  herd,  as 
they  may  introduce  the  disease  to  your  farm. 

If  animals  are  fluked,  send  those  which  are  most  affected  to  the 
butcher  and  place  the  others  on  dry  ground. 

Destroy  the  livers  of  the  slaughtered  animals,  or  if  used  as  food  for 
animals  (dogs,  etc..)  they  should  first  be  cooked  in  order  to  kill  the 
eggs;  if  this  precaution  is  not  taken,  the  fresh  eggs  will  pass  through 
the  intestine  of  the  dog  uninjured  and  be  scattered  over  the  fields. 

Manure  from  fluky  animals  should  never  be  placed  upon  wet  ground. 
It  is.  however,  not  dangerous  to  use  such  manure  upon  dry  ground. 

As  rabbits  and  hares  may  introduce  the  disease  into  a  district,  or 
may  keep  up  an  infection  if  once  introduced,  these  animals  should  be 
kept  down  as  much  as  possible.  This  is  not  always  practicable.  (This 
precaution  does  not  apply  to  Hawaii  in  so  far  as  rabbits  and  hares  are 
concerned  but  is  most  important  as  regards  the  wild  goats  and  swine.) 

Where  animals  very  heavily  infested  with  flukes  have  pastured  on  a 
given  piece  of  ground,  some  one  should  go  over  the  field  with  a  spade 
and  spread  out  the  patches  of  manure,  so  that  it  will  dry  more  rapidly, 
and  thus  the  eggs  may  be  more  quickly  destroyed.  A  spade  full  of 
lime  or  dust  will  aid  in  drying  up  the  manure  patches.  (Applies  only  to 
dairy  herds  in  Hawaii.  It  is  a  good  point  to  mention  in  this  connection 
that  this  practise  will  also  be  fatal  to  the  eggs  of  the  horn-fly.  depos- 
ited in  the  fresh  manure  by  the  adult  fly.) 

Manure  of  fluky  animals  should  not  be  stored  where  it  can  drain  into 
pastures, 


To  control  marshy  ground: 

The  marshes  should  be  drained,  if  possible,  so  that  the  snails  may 
be  gotten  rid  of. 

It  has  been  noticed  that  sheep  which  pasture  on  salt  marshes  are 
not  fluked;  accordingly  dressings  of  salt,  to  which  lime  may  be  added, 
should  be  spread  over  the  pasture,  as  salt  and  lime  will  destroy  the 
embryos,  the  encysted  cercariae,  and  the  snails.  .    .    . 

Lime  will  destroy  the  grass  for  immediate  use,  but  will  in  some 
cases  be  advantageous  to  the  soil.  .    .    . 

If  the  marshy  ground  cannot  be  controlled,  place  the  animals  on 
higher  ground.  (This  also  does  not  generally  apply  to  Hawaiian  con- 
ditions, since  in  many  places  the  constant  moisture  of  the  higher  alti- 
tudes renders  the  conditions  ideal  for  the  life  of  the  snail  and  the 
development  of  the   parasite.) 

To  destroy  the  snail. — This  may  be  done  by  draining  the  fields,  thus 
depriving  the  snails  of  the  conditions  necessary  for  their  development, 
or  by  the  free  use  of  salt  and  lime. 

General  precautions  to  be  taken: 

It  is  known  that  salt  will  kill  the  cercariae;  accordingly  if  salt  is 
given  to  the  animals  they  stand  a  better  chance  of  escaping  hepatic 
(fluke)  infection,  even  if  the  germs  are  swallowed,  not  only  because 
this  substance  kills  the  young  flukes,  but  because  it  aids  the  animals 
in  their  digestion.  (The  value  of  feeding  salt  to  fluke-infested  stock 
has  been  proved  by  experiments  noted  in  this  connection  but  which 
are  not  quoted.) 

A  daily  allowance  of  dry  food  should  be  given. 

If  fields  are  overstocked  the  animals  will  be  obliged  to  graze  very 
close  to  the  ground,  and  will  thus  be  more  liable  to  become  infected, 
accordingly,  in  order  to  prevent  this  close  grazing,  fields  should  not  be 
overstocked. 

Animals  should  not  be  left  too  long  upon  the  same  pasture. 

Raised  watertanks  .should  be  placed  in  the  pastures  so  that  the  herds 
will  not  be  forced  to  drink  from  pools,  etc.  As  it  is  difficult  for  snails 
to  get  into  such  drinking  tanks,  there  will  be  little  fear  of  infection 
from  tanks  of  this  sort. 


Tared   G.    Smith, 
D.  L.  Van  Dine. 


Honolulu,  T.  H.,  January  5.  1905. 


EXPLANATION    OF    PLATE   I. 


The  Life-Cycle  of  the  Liver-Fluke,  Distoma  hepaticum.  A.  —  Egg  of 
the  common  liver  fluke  containing  a  developed  embryo.  Magnified  130 
diameters.  B, — Egg  after  hatching.  C,— The  ciliated  embryo  ae  it 
appears  before  attacking  the  fresh-water  snail.  Magnified  about  350 
diameters.  D, — A  sporocyst  which  has  developed  from  the  embryo 
within  the  body  of  the  snail,  in  which  may  be  seen  the  developing 
rediae.  Magnified  200  diameters.  E, — Redia  in  the  liver  of  the  snail 
with  developed  cercariae.  Magnified  150  diameters.  F, — Encysted 
cercariae  on  a  portion  of  a  grass  stalk.  Magnified  10  diameters. 
G, — Young  of  liver  fluke  which  has  developed  from  cercariae  in  liver 
Of  stock.  Natural  size.  H, — Adult  liver  fluke  from  liver  of  stock. 
Natural  size.  I  and  J, — The  fresh-water  snail,  Limnaea  oahuensis,  an 
intermediate  host  of  the  liver  fluke.  Slightly  enlarged.  (A,  B,  C,  G 
and  H  copied  from  Neuman's  Parasites  and  Parasitic  Diseases  of 
Domesticated  Animals.  D,  E,  F,  I  and  J  copied  from  Bulletin  19, 
Bureau  of  Animal  Industry,  U,  S.  Department  of  Agriculture.) 


PLATE     I. 


UM/VERS/ 


11 0F  n< 


■»»»piiii 


3  1262  089297lTj' 


